In order to prevent an unauthorized access to a vehicle, particularly a motor vehicle, modern access authorization systems or access arrangements in vehicles use electronic security systems in which a data communication between a first communication device of the vehicle with a second communication device in a mobile identification transmitter of a user such as a key or a key fob takes place for authenticating a user. When the access arrangement is active, the mobile identification transmitter sends control signals and an identification code, for example, by pressing a certain key by the user of the mobile identification transmitter, to the vehicle whereupon the latter is unlocked or locked, respectively, when the identification code is correct.
In the case of a so-called passive access arrangement, a first communication device of the vehicle first sends out query signals of a particular field strength at regular time intervals in order to check whether a mobile identification transmitter is located within an approach or acquisition region around the vehicle. If a mobile identification transmitter approaches the vehicle and is ultimately able to receive its query signals, it will respond to the reception of a query signal with a corresponding response signal in order to initiate an authentication process or preauthentication process. During this process, data are exchanged in which, in the end, the mobile identification transmitter conveys its authentication code to the vehicle. If the check of the authentication code is successful, it is then possible that a user who is located directly at the vehicle achieves unlocking of the corresponding vehicle door or of all vehicle doors by operating a door handle. Since in this case no active operating of a mechanical or electrical identification transmitter or key needs to be carried out by a user, this type of access authorization is also called passive access authorization check and the corresponding access authorization systems are called passive electronic access authorization systems.
However, in the case of such a passive access arrangement just described, the following problematic situation may occur. A user or driver parks his vehicle in the garage and leaves the vehicle. He then hangs his jacket, in which he has unintentionally kept his key, in the garage in the vicinity of his vehicle on a hook and leaves the garage. As has already been mentioned above, the vehicle continues to send out query signals at regular time intervals which are received by the key in the jacket since it is within the acquisition region or approach region of the vehicle. In other words, the key is woken by each query signal of the vehicle, generates a response signal and sends it back to the vehicle. Although this is not associated with any desire of a driver to perform an authentication in order to be able to enter the vehicle, the regular waking by a query signal and sending out a corresponding response signal consumes current unnecessarily in the key which reduces the service life of the key or of the identification transmitter, respectively. Furthermore, current is also consumed unnecessarily in the vehicle by the receiving and processing of the corresponding response signals.